Older cancer survivors are faced with age- and treatment-related comorbidities, including physical functional impairment, which are exacerbated by physical inactivity and sedentary behavior. There is a critical need for physical activity interventions that are effective and accessible to older survivors from diverse backgrounds that are designed to be feasible, relevant, and meaningful for them. The goal of this K07 Mentored Career Development Award is to assist Cindy Blair, PhD, with becoming an independent investigator, specializing in home-based interventions to improve the health and well-being of underserved cancer survivor populations. Specifically, Dr. Blair will develop expertise in the design and dissemination of home-based interventions that utilize a whole-of-day approach to physical activity in older cancer survivors. This approach focuses on increasing light-intensity activity throughout the day, while reducing and disrupting sedentary activity. Her short- term goals include specialized training in 1) working with underserved cancer survivor populations ? older, rural, and ethnic minority; 2) existing and emerging technology for remote assessment of physical performance; and 3) design, implementation, and evaluation of home-based behavioral randomized controlled trials (RCT). To achieve her goals and enhance her expertise, Dr. Blair will receive focused mentorship from established investigators and participate in formal coursework and workshops, directed learning experiences, seminars, and national conferences. RESEARCH: The research plan includes a validation study and a feasibility RCT. First, we will evaluate the accuracy and reliability of using videoconferencing to remotely assess physical performance. Second, we will examine the feasibility and acceptability of a novel home-based intervention to promote light- intensity activity and reduce sedentary activity using a whole-of-day approach. Sixty-four older cancer survivors (50% Hispanic; 50% rural) will be randomized to either a 16-week theory-based intervention or a modified waitlist control. The intervention uses an electronic activity monitor that pairs with a smartphone app to promote awareness and enable self-monitoring of both activity and inactivity. Motivational counseling will be used to individually tailor strategies to achieve goals. Data will be collected at baseline, post-intervention, and 6-months post-intervention. The primary outcomes include recruitment, retention, adherence and physical function; secondary outcomes include physical performance, objective measures of physical activity and sedentary behavior, and self-reported quality of life. The results of this trial will inform the design of a definitive R01-funded RCT to detect clinically meaningful and statistically significant effects. Completion of the proposed training and research plan will prepare Dr. Blair to successfully compete for NIH R01 funding and establish an independent research program to promote (light-intensity) physical activity using a whole-of-day approach in older cancer survivors.